Overwriting and adding Built-in Functions and Tags
Overwriting and Adding Built-in Functions and Tags
In Lucee, you can overwrite or add built-in functions and tags with your own implementations. This is particularly useful for emulating the behavior of older Lucee versions in newer ones or for backporting fixes to older versions.
Overwriting/Adding Functions
Let's consider an example with the val function. The behavior of val was updated in Lucee 6.1 to more closely align with Adobe ColdFusion (ACF). To replicate this updated behavior in versions prior to 6.1, follow these steps:
Create a file at …/lucee-server/context/library/function/val.cfm with the following content:
<cfscript>
public numeric function val(required obj) {
if (!structKeyExists(server, "functionVal")) {
lock name="functionVal" {
if (!structKeyExists(server, "functionVal")) {
server.functionVal = createObject("java", "lucee.runtime.functions.string.Val");
}
}
}
try {
return server.functionVal.call(getPageContext(), obj);
} catch (e) {
return 0;
}
}
</cfscript>
After creating this file, restart Lucee. This custom implementation of the val function will now be used throughout your code. In this example, the original val function is called, but any exceptions are caught, and 0 is returned if an exception occurs.
This approach not only allows you to overwrite existing functions but also to add entirely new functions that will behave like built-in functions. You can find many built-in function templates in the …/lucee-server/context/library/function/ directory.
Overwriting/Adding Tags
The process for tags is similar. To create or overwrite a tag, use the …/lucee-server/context/library/tags directory. Custom tags need to follow the same interface as regular custom tags. You can refer to existing built-in tags in this directory as templates for your implementations.
By following these steps, you can extend or modify Lucee's capabilities to suit your specific needs.